Container crown ring inspection apparatus having means disposed between lamps and crown ring for obstructing radial rays from lamps

ABSTRACT

A crown ring defect inspection apparatus for beverage containers and the like comprising automatic inspection means for detecting crown ring chips and irregularities in a moving line of containers and rejecting the defective containers. The apparatus includes photoelectric means for examining each container as well as photomultiplier means responsive to optical signals for converting such signals to electrical signals which actuate the reject mechanism.

United States Patent [72] Inventors James R.Gcnder Kirkwood; Leonard V.Makela, Chesterfield; Karl Wolf, Webster Groves, all of Mo. [21] Appl.No. 90,044 [22] Filed Nov. 16, 1970 [45] Patented Dec. 28, 1971 [73]Assignee Barry-Wehmlller Company St. Louis, Mo.

Continuation of application Ser. No. 773,759, Nov. 6, 1968, nowabandoned. This application Nov. 16, 1970, Ser. No. 90,044

[54] CONTAINER CROWN RING INSPECTION APPARATUS HAVING MEANS DISPOSEDBETWEEN LAMPS AND CROWN RING F OR OBSTRUCTING RADIAL RAYS FROM LAMPS 5Claims, 10 Drawing Figs.

[52] U.S. Cl 250/223 B, 209/11 1.7, 250/237, 356/240 [51] Int. Cl 6011121/32,

606m 7/00, HOlj 39/12 [50] Field of Search 356/240, 237; 250/223 13,217, 237; 209/1 1 1.7

[56] References Cited UNITED STATES PATENTS 2,411,991 12/1946 England etal. 356/237 3,191,773 6/1965 Wyman 209/111.7 3,302,787 2/1967 Rottmann250/223 B 3,349,906 10/1967 Calhoun et al.. 250/223 B 3,479,514 11/1969Kidwel] 356/240 X Primary Examiner-Archie R. Borchelt AssistantExaminer-T. N. Grigsby Attorney-Gravely, Lieder & Woodruff ABSTRACT: Acrown ring defect inspection apparatus for beverage containers and thelike comprising automatic inspection means for detecting crown ringchips and irregularities in a moving line of containers and rejectingthe defective containers. The apparatus includes photoelectric means forexamining each container as well as photomultiplier means responsive tooptical signals for converting such signals to electrical signals whichactuate the reject mechanism.

PATENTED 05328 ISTI SHEET 2 BF 4 FIG .4

imam r025. J4M$ 1?. 654 252 PATENTED BEC28 lsn SHEET 4 OF 4 FIG 8 FIG]CONTAINER CROWN RING INSPECTION APPARATUS HAVING MEANS DISPOSED BETWEENLAMPS AND CROWN RING FOR OBSTIRUCTING RADIAL RAYS FROM LAMPS Thisapplication is a continuation of application Ser. No. 773,759 filed Nov.6, 1968 and now abandoned.

The invention relates to apparatus for detecting defects in containercrown rings while moving in a high capacity conveyor system and forrejecting the defective containers before the latter are filled.

The crown ring portions of containers in one form of this invention maybe inspected by optically projecting an image of the crown ring througha prism of rotating character onto a photomultiplier tube which convertsdefects in the optical image into electrical signals suitable foroperating reject mechanism that withdraws the defective container from aline of moving containers. In an equivalent system the containers passthrough an inspection station where the crown rings are illuminated bylight from a predetermined source, and the illuminated image is viewedby a photomultiplier tube or by photocells which react to create asignal that is then used to initiate reject mechanism operation.

The objects of this invention are to detect or inspect for defectivecontainer crown rings while moving at high speed so as not to retard thecapabilities of filling and capping equipment; to provide efficient andcertain means for accomplishing the inspection function in a moving linecontainers; to provide simple and compact inspection apparatus that willavoid false signals; and to provide apparatus teat will acceptcontainers without regard to color or size.

Other objects and advantages of the apparatus will be more particularlyset forth in the following disclosure which is given in connection withthe accompanying drawings, wherein;

FIG. I is a sectional elevational view of a certain preferred embodimentof the invention showing the character and assembly of the variouscomponents;

FIG. 2 is a fragmentary and enlarged view of the apparatus seen at line22 in FIG. 1;

FIG. 3 is a view taken along line 33 in FIG. 1 looking upwardly at thelighting unit;

FIG. 4 is a sectional view taken at line 4-4 in FIG. I to shown certaininterior details of the lighting unit;

FIG. 5 is a greatly enlarged and fragmentary view of lighting meansshowing the manner in which it functions to illuminate a container crownring;

FIG. 6 is a fragmentary and schematic view of the light deflectingaction of one light source in the organization shown in FIG. 5;

FIG. 7 is a fragmentary sectional elevational view of a modification ofthe apparatus seen in FIG. 1;

FIG. 8 is a view similar to FIG. I but showing a modification of thepresent invention;

FIG. 9A is a block diagram of an electronic circuit incorporating thesignal producing means of the apparatus of FIG. I; and

FIG. 9B is a view similar to FIG. 9A but modified to suit therequirements of the apparatus of FIG. 8.

As is seen in FIGS. I and 2, the handling of the containers C isachieved by a flat chain type conveyor 10 of known construction havingsuitable guide rails 11 and Ila supported by brackets I2. The containersare moved on the conveyor 10 into and out of an inspection stationdefined by a pair of star wheels 13 and 14 mounted on a vertical shaft15 for rotation in a horizontal plane. The star wheel 13 has a peripheryformed with recesses to receive the bodies of a succession ofcontainers, and the star wheel 14 has peripheral recesses 16 (FIG 2) tomesh with the neck portions of the containers. The shaft 15 carries ahub I7 which carries a plurality of suction cups I8 equal in number tothe recesses in the star wheels 13 and 14. Each suction cup iscontrolled by a suitable valve mechanism 19 associated with vacuum meansnot shown but thoroughly set forth in Drennan US. Pat. No. 2,800,226,issued July 23, I957. As each container C approaches the inspectionstation a meshing shield wheel 20 is engaged by the neck portion so thatat the time of inspection of the container crown ring CR the containeris fully shielded from ambient light such as light below the crown ring.The shield wheel 20 is rotatably mounted on a yieldable arm 21 carriedby a suitable bracket 22 and spring pressed against an adjustable stop22a (FIG. 2).

In the view of FIG. I, the apparatus in the inspection station includesa stationary frame 23 which supports a housing 24 which carries suitablebearings 25 for a rotary tube 26 within which a Dove prism 27 ismounted. The tube 26 is rotated by a belt 28 driven from pulley 29 onthe shaft ofa motor 30 supported in a housing 3I. the speed of rotationof the prism being approximately 8,800 r.p.m. The prism 27 is axiallyaligned with a collimating lens 32 mounted over an aperture 33 in theframe 23, and the upper end of the housing 24 carries an enclosure 34 inwhich a second collimating lens 35 is supported in a lens tube 36. Theenclosure 34 carries a light energy receiver such as photomultipliertube 37 separated from the lens tube 36 by a wall 38 in which anelongated aperture 39 is provided (see FIG. 5)

Associated with the foregoing components is an iliumina tion unit 40which is mounted below t he frame 23 in the inspection station. The unit40 includes a base 41 having a central aperture 410 and on which aremounted (FIG. 4) a plurality of light energy producing lamps 42. In thisview each lamp is provided with a light projecting lens tip as anintegral part. The lamps 42 are arranged in circumferentially spacedrelation and are also divided into two groups on either side of thearcuate path of travel of the container crown rings, the path beingindicated by the curved arrow A in FIGS. 3 and 4. The lamps 42 directthe light energy radially inwardly toward the center of the base wherethe container crown ring CR is inspected at aperture 410. An importantfeature of the unit 40 is in the provision of light ray shield means 43and blocking pins 430 radially inwardly of the shield for each lamp 42.The lamps 42 being located behind the curved light shield 43 which hasapertures 43b for light rays to pass through (see FIG. 4) Light raysemanating from the sides of the lamps will be prevented from reachingthe crown ring zone. The lamps 42 are enclosed by a pair of black-linedcovers 44 and 45 spaced by arcuate margins 44a and 450 respectively toform a lane through which the container crown ring CR moves (FIG. 3).The covers are secured in position by screw posts 46. Thus, the lamps 42are closed in to provide a black box effect.

The apparatus above described inspects each container crown ring CRwhile the container is in motion on the conveyor 10 by projecting aplurality of light beams form lamps 42 upon the crown ring. The light isreflected upwardly only by a light deflecting flaw and passes throughthe lens 32 where it is rotated by the action of the Dove prism 27 andis passed by the latter through the lens 35 toward the aperture 39 whichis an elongated slit having a radial orientation relative to the crownring CR. The radial slit directs a sector of light onto thephotomultiplier tube 37 where it appears as a light blip and isconverted into an electrical signal. A container free of crown ringflaws will not deflect light upwardly. As can be appreciated the lightsources 42 are arranged in a circle in substantially the same plane withthe crown ring CR and centered on the container axis in the inspectionstation. Each lamp 42 produces a divergent beam of light B (see FIGS. 5and 6) having an effective rectangular cross section. Located in frontof each lamp is the shield 43 to block stray light from adjacent lamps,and inwardly of the shield the blocking pin 43a obstructs the centralportion of the beam.

Attention will now be directed to FIGS. 5 and 6 for a more detailedexplanation of the operation of the unit 40, and in the view of FIG. 5the slit 39 adjacent the photomultiplier tube 37 is superimposed inphantom outline. Each light B diverges toward the crown ring CR, but thecentral radial portion R is blocked so the portions on each side strikethe crown ring at angles approaching the tangent. The angled light isdeflected off in various directions D, none of which is directedupwardly in the axis of the container C. As a result a shadow S iscreated by each blocking pin 43a, but the two adjacent lamps willilluminate the shadow area without producing an axial deflection. It isalso to be understood that the action of the Dove prism 27 is to see theentire image of the crown ring CR and to rotate that image two completerevolutions for each revolution of the prism. Thus, for a rotary speedof 8,800 r.p.m. the effective speed of rotation of the image is 17,600rpm.

When a nondefective container crown ring CR is in the inspeetion station(FIGS. 4 and 5) all of the light beams are reflected by the surfaces andare bounced off in directions D (FIG. 6) nonparallel to the verticalaxis of the container or Dove prism 27. These beams are not seen by thephotomultiplier tube 37, either collectively or individually, becausethe blocking pins 430 obstruct the direct radial portions R of each beamB (FIG. 5) which would be reflected axially upwardly to thephotomultiplier tube 37. Thus, each pin 43a casts a shadow S on thecrown ring CR, but as before noted, each adjacent lamp delivers aportion of its beam on each side so that the beams overlap laterallybehind the pins (on the crown ring side) to illuminate the crown ringaround its complete circumference without having any portion reflectedaxially upwardly. As a result, the photomultiplier tube 37 secs darknessas long as the crown ring CR is not defective. When, however, a flaw ispresent the light deflected from the flaw is changed in direction and abeam directed axially upwardly results and this portion of the deflectedlight is picked up in the prism 27 and passed to the photomultipliertube 37 as a sector of the crown ring CR.

In order to minimize backgroundand ambient light that 30 might causefalse signals, the top surfaces of the star wheel 14 and the shieldwheel 20 are black finished for maximum light absorption, the wheel 20being provided to block out the photomultiplier tube field of view ofthe conveyor and approaching and receding containers. Proper meshing ofthe wheel 20 is provided by the spring tension on the arm 21 whichallows swinging to adjust the mesh.

The spring keeps arm 21 forced against the adjustable stop 22a whichlimits arm travel. The stop is adjusted such that the shield star wheel20 is in proper position for meshing. If meshing fails to occur, the arm21 pivots backward to prevent jamming of containers. As soon as meshingcan resume, the spring forces the shield star wheel 20 into meshingposition via the arm 21 and the adjustable stop 22a.

Returning now to FIGS. 1 and 2 it can be seen that the illumination unit40 carries inwardly of cover 45 a photocell 47 which is adjustablypositioned relative to and aligned with an elongated aperture 48 incover 45. The photocell receives a signal light beam through slots 49 inthe star wheel 14. The source of the signal beam is the lamp 51 carriedon a support arm 52 attached to a bracket 53. The photocell 47 can beshifted relative to slot 48 for adjustment of the timing of registrationof the container crown ring CR at the inspection station. Pivoting ofbracket 53 permits alignment of lamp 51 under the slots 49 for thephotocell 47. As can be seen in FIGS. 1 and 2, the star wheel 13 is aring suspended from star wheel 14 by hanger rods 54 suitably locatedbetween the suction tubes for the cups 18. The star wheels 13 and 14 arethus coupled together by the rods 54 for rotatory movement together whenengaged by the containers impelled by the conveyor 10. The number ofslots is equal to the number of container recesses 16 so that as eachrecess is about to reach the inspection station the photocell 47 willgenerate a signal for a purpose to appear. 55

A block diagram of the electrical circuit for the inspection apparatusof FIG. 1 is seen in FIG. 9A and reference is directed thereto. Thephotomultiplier tube 37 which converts the optical image signal from theDove prism 27 to electrical signals may be an RCA 7] l7, and isconnected in a standard circuit as recommended. The tube 37 is poweredthrough a resistor network 55 by an adjustable high voltage power supply56 of 400-800 v. The tube output is connected through a high passnetwork 57 to the first amplifier stage of an amplifier and frequencysensitive network 58. The high pass filter 57 is required to reduceunwanted signals mainly those at 60 and Hz. in the power supply and atapproximately 300 Hz. caused by the Dove prism rotation speed.

The frequency adjust control 58a is part of an RC network between thefirst and second amplifier stages, and gives some control over the highfrequency response of the amplifier. As the control is set lower thefrequency response is reduced, and this reduces sensitivity to smallcontainer defects. The gain control 58b adjusts the output of the secondamplifier stage, and is used to adjust overall system sensitivity. Asuitable mixer 59 is connected to follow the frequency sensitive network58.

A gating signal is produced by the photocell 47 (FIG. I) which is asilicon photovoltaic cell and is timed to container position to triggera monostable multivibrator 60 through a Schmidt trigger switch 61, andprovides the timed pulse during which crown ring inspection takes place.The gating signal allows the mixer 59 to pass signals only during theinterval when the crown ring CR is being scanned, and the position ofthe photocell 47 on the illumination unit 40 is adjustable, so that theoptimum turn-on time can be selected. The monostable multivibrator 60has an ON time of approximately 4 milliseconds, but any time greaterthan about 3.4 milliseconds is deemed satisfactory. The longer the ONtime, the slower the conveyor 10 must be traveling in order that thecrown ring remains in view during the scan time. About a 4 millisecondscan time has been found satisfactory for conveyor speeds of about 25inches a second.

The circuit includes a coincidence gate which receives both the outputsignals from the amplifier 58 and from the gate pulse generator 60. Whenboth signals are simultaneously received, a reject signal is sent to areject monostable multivibrator 62 and then to the solenoid controlcircuit 63 which includes a Triac thyristor. The Triac thyristorcontrols the power sent to the reject solenoid 64 which is not shown inFIG. 1, but is part of the operating components of the suction systemassociated with the suction cups 18. Though not shown a suitable powersupply is provided for the plurality of lamps 42 and for the gate lamp51.

Turning now to FIG. 7, there is shown a modification of the apparatus ofFIG. 1 in which the like parts are indicated by similar referencenumerals. The difference in the apparatus of FIG. 7 to that in FIG. 1resides in the simplification of the rotating means. In place of therotating prism 27, the tube 26 now supports a mask 38a having theaperture or slit 39a therein. A focusing lens 32a is mounted axiallyabove the station for the crown ring CR and focuses the illuminationdeflected by a flaw upon the aperture 39a. The light sensitivephotomultiplier means 37 is, in this modified embodiment, still exposedto a light sector that rotates relative to it and to the crown ringbecause of the circular orbit imparted to the aperture or slit 390. Inother respects the apparatus of FIG. 7 functions in the same wayheretofore described in connection with FIG. 1.

In FIG. 8 a modified crown ring defect detector has been shown. Wherepossible parts and components like those shown in FIGS. 1 and 2 will bepointed out by like reference numerals, and only so much of the assemblywill be described as is believed necessary to a full understanding ofits operation. The containers C are conveyed as in FIG. 1 and engagestar wheels, such as star wheel 14. The shield star wheel 20 is i in thestar wheel. Each pin 68 has an upper polished end face 69 to reflectlight conducted thereto from a lamp 70 through a clear plastic tube 71.The light reflected from the polished faces 69 is picked up in a clearplastic rod 72 carried in the tube 71 and directed to a photocell 73.The photocell 73 is mounted on the end of the rod 72 to collect all ofthe light from the lamp 70 which reaches the plastic rod 72. The tube 71is carried by an arm 74 and the lamp 70 is supported by an arm 74a. Thepins move with the star wheel 14 and sense the position of thecontainers relative to the inspection station.

Over the inspection station the frame 23 heretofore described carriesthe optical means in which a rotating Dove prism 27 and fixedcollimating lenses 32 and 35 are included. The image of the crown ringCR is viewed through the slit 39 by the photomultiplier tube 37. Inplace of the illuminating unit 40, a modified unit 75 is mounted on theframe 23 over the aperture 33. This unit includes a suitable housing 76having an upper aperture 76a and in which is mounted a cold cathode lamp77 in a conical shape. The bottom of the housing 76 is provided with anapertured mask 78 which is positioned close to the crown ring. In a testapparatus the mask was set about one fourth inch above the crown ringand had an aperture of about one and three-fourths of an inch. Thecollimating lens 32 is desirably positioned at its focal length abovethe claimed is: ring, and the size of opening for this lens 32 isselected to control the amount of light entering the Dove prism 27 sothat the collimated light rays are at a maximum usable levelcommensurate with the light required by the photomultiplier tube 37 todetect defects.

As before noted, the Dove prism is rotated by a belted motor and rotatesat approximately 8,800 r.p.m. for optimum scanning. In this modificationof FIG. 8 the upper lens 35 focuses the light rays from Dove prism in asharp image at the slit 39, and the slit is located to one side of thecrown ring image, as is indicated in phantom in FIG. 5. The dimensionsof the slit 39 are selected so that at the highest speed of the conveyor10, a half revolution of the Dove prism will give a complete scan of thecrown ring CR without any part being missed clue to conveyor movementand unwanted motions of the star wheel assembly.

In the modification, the light passing through the slit 39 is convertedby the tube 37 to an electrical signal proportional to the overall lightamplitude. The signal from tube 37 is the input to the electroniccircuit system shown in FIG. 9B, the circuit being similar to thecircuit described for FIG. 9A with the following differences. The coldcathode lamp 77 is excited with DC supply, since operation from the 60Hz. power source gives 60 and 120 Hz. variations in light amplitude. Inoperation, the photomultiplier tube 37 sees a complete circle of lightwhen there is no defect, but when a defect appears, the ring of light isintercepted and less light is transmitted. This decrease is sensed toproduce the signal for energizing the reject solenoid 64. Some defectscause the ring to be locally enlarged thus increasing the amount oflight transmitted. Thus, this requirement is met by inserted a phasesplitter 65. Since crown ring defects can cause either dark or lightspots, the signal caused by the defect can be a pulse in either positiveor negative direction. Therefore, the phase splitter 65 follows theamplifier to give two outputs, one being inverted with respect to theother. In this manner, either type of defect signal gives a positivepulse to the mixer circuit 59. In the mixer 59 the phase splittersignals are combined so that either type of defect could trigger thereject monostable multivibrator 62.

The present invention has been set forth in certain preferredembodiments and each exhibits a stationary source of light energydirected toward the crown ring CR as each container is moved through theinspection station. The light energy receiving means 37 is alsostationary relative to the crown ring and the light source 40 or 75 (asthe case may be). The scanning function for each crown ring CR isaccomplished by the rotating mask 38a or prism 27 in conjunction withthe mask 38. The action of the prism is preferred as it gives a veryhigh rate of scan while each container is in the inspection station fora short time. The prism also avoids the need to rotate the containers.The two examples 40 and 75 ofillumination units will suggest thepossible use of other equivalent energy producing means which is subjectto modulation by crown ring defects and flaws and thereby deflected intothe axis of the scanning means.

Therefore, changes and modifications thereof which do not representdepartures from this disclosure are intended to be included within thescope of the appended claims.

What is claimed is 1. Apparatus for inspecting container crown rings forlight deflecting flaws comprising: means to continuously move containersalong a known path in preparation for inspection of the crown ring; astationary source of light adjacent the plane of the path of movement ofthe crown ring portion of containers, and said light source including aplurality of lamps and obstruction means disposed between each lamp andthe crown ring to obstruct the radial portion of the light rays fromilluminating the crown ring so that light on either side of radial raysis deflected by crowning flaws out of said plane in a directionsubstantially axially outwardly of the crown ring and during containermovement making a flaw appear as a bright area relative to other areasof the crown ring; stationary light sensing means disposed axiallyopposite said predetermined place along the path of container movement;and means disposed axially outwardly of the crown ring and operativebetween said sensing means and the source of light to expose successiveportions of the crown ring to said sensing means.

2. Apparatus for inspecting containers for light deflecting flaws in thecrown ring comprising: a crown ring illuminating unit including ahousing having a first opening adjacent which the container crown ringis disposed and a second opening axially spaced from said first opening,and lamp means in said housing arranged in spaced array around theinterior to direct a beam of light radially upon the crown ring adjacentsaid first housing opening to illuminate substantially the entirecircumferential extent of the crown ring; beam blocking means for eachlamp set axially between a lamp and the approximate center of the crownring, whereby the light beams from each said lamp are effective toilluminate portions of the crown ring at either side of the axial beampath; illumination sensing means positioned axially beyond said secondopening so as to be spaced from the crown ring; means disposed betweensaid second opening and said sensing means to project an image of theilluminated crown ring toward said sensing means, said image projectingmeans including a rotating prism which rotates the illuminated crownring image; and a mask intercepting the illuminated crown ring imageprojected toward said sensing means, said mask having a slit therein topass only a sector at a time of the illuminated image, whereby saidsensing means scans the image sector and said rotating prism rotatessuccessive sectors of the illuminated image past said slit.

3. The apparatus of claim 2 and including means to engage each containerpositioned adjacent said first housing opening and form a shield againstambient light entering said first opening.

4. The apparatus of claim 1 wherein said last means includes a Doveprism rotatable in the axis of the outwardly directed light, and astationary mask having a slot therein directed radially of a segment 0the entire crown ring.

5. Apparatus for inspecting container crown rings for flaws whichdeflect light in a direction axially of the container comprising: acrown ring illuminating unit having discrete sources of lightsurrounding a predetermined zone; light obstructing means for eachdiscrete light source positioned to obstruct the radially directedportion of the rays of light directed toward each container crown ringmoved through said predetermined zone; means at one side of said zoneand engaged by successive containers for shielding the light fromdilution by ambient light; means to move containers past saidilluminating unit in position with crown rings passing through said zoneto be illu minated by said discrete sources of light; means at the sideopposite said shield and axially beyond the crown ring to scan the zonefor light directed out of said zone by the crown ring, said scan meansincluding a photoelectric element responsive to light received therebyand rotating viewing means between said photoelectric element and saidzone to expose successive sectors of said zone to said element, wherebylight directed from a crown ring flaw is passed to said photoelectricelement.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 1:;1; Dated Inventor(s) James R. Gender and Leonard V. Makela Itis'certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Col. 2, line 48, after "beams" and before "lamps",

cancel "form" and substitute "form";

Col. 5, line 15, at the beginning of the line, after "the", cancel"claimed is" and substitute "crown";

Col. 6, line 11, after "by" and before "flaws", cancel "crowning" andsubstitute "crown ring";

Signed and sealed this 18th day of July I 972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-105O (10-69) USCOMM-DC 60376-P69 s us. GOVERNMENTPRINTING OFFICE: I969 0-355-334

1. Apparatus for inspecting container crown rings for light deflectingflaws comprising: means to continuously move containers along a knownpath in preparation for inspection of the crown ring; a stationarysource of light adjacent the plane of the path of movement of the crownring portion of containers, and said light source including a pluralityof lamps and obstruction means disposed between each lamp and the crownring to obstruct the radial portion of the light rays from illuminatingthe crown ring so that light on either side of radial rays is deflectedby crowning flaws out of said plane in a direction substantially axiallyoutwardly of the crown ring and during container movement making a flawappear as a bright area relative to other areas of the crown ring;stationary light sensing means disposed axially opposite saidpredetermined place along the path of container movement; and meansdisposed axially outwardly of the crown ring and operative between saidsensing means and the source of light to expose successive portIons ofthe crown ring to said sensing means.
 2. Apparatus for inspectingcontainers for light deflecting flaws in the crown ring comprising: acrown ring illuminating unit including a housing having a first openingadjacent which the container crown ring is disposed and a second openingaxially spaced from said first opening, and lamp means in said housingarranged in spaced array around the interior to direct a beam of lightradially upon the crown ring adjacent said first housing opening toilluminate substantially the entire circumferential extent of the crownring; beam blocking means for each lamp set axially between a lamp andthe approximate center of the crown ring, whereby the light beams fromeach said lamp are effective to illuminate portions of the crown ring ateither side of the axial beam path; illumination sensing meanspositioned axially beyond said second opening so as to be spaced fromthe crown ring; means disposed between said second opening and saidsensing means to project an image of the illuminated crown ring towardsaid sensing means, said image projecting means including a rotatingprism which rotates the illuminated crown ring image; and a maskintercepting the illuminated crown ring image projected toward saidsensing means, said mask having a slit therein to pass only a sector ata time of the illuminated image, whereby said sensing means scans theimage sector and said rotating prism rotates successive sectors of theilluminated image past said slit.
 3. The apparatus of claim 2 andincluding means to engage each container positioned adjacent said firsthousing opening and form a shield against ambient light entering saidfirst opening.
 4. The apparatus of claim 1 wherein said last meansincludes a Dove prism rotatable in the axis of the outwardly directedlight, and a stationary mask having a slot therein directed radially ofa segment o the entire crown ring.
 5. Apparatus for inspecting containercrown rings for flaws which deflect light in a direction axially of thecontainer comprising: a crown ring illuminating unit having discretesources of light surrounding a predetermined zone; light obstructingmeans for each discrete light source positioned to obstruct the radiallydirected portion of the rays of light directed toward each containercrown ring moved through said predetermined zone; means at one side ofsaid zone and engaged by successive containers for shielding the lightfrom dilution by ambient light; means to move containers past saidilluminating unit in position with crown rings passing through said zoneto be illuminated by said discrete sources of light; means at the sideopposite said shield and axially beyond the crown ring to scan the zonefor light directed out of said zone by the crown ring, said scan meansincluding a photoelectric element responsive to light received therebyand rotating viewing means between said photoelectric element and saidzone to expose successive sectors of said zone to said element, wherebylight directed from a crown ring flaw is passed to said photoelectricelement.